US Secretary of State John Kerry on Thursday announced a fresh international peace initiative for Yemen aimed at forming a unity government to resolve its 17-month-old conflict.

"This war needs to end and it needs to end as quickly as possible," Kerry said after a meeting in Saudi Arabia with Gulf counterparts, a British minister and the UN peace envoy to Yemen.

He said participants "agreed on a renewed approach to negotiations" between the Saudi-backed government and Iran- supported rebels, after three months of talks in Kuwait ended earlier in August without making headway.

Kerry lashed out at Iran, saying its arms shipments to the Shiite Huthi rebels in Yemen posed a threat to the United States.

"The threat potentially posed by the shipment of missiles and other sophisticated weapons into Yemen from Iran extends well beyond Yemen and is not a threat just to Saudi Arabia and… the region," Kerry told reporters in the Red Sea city of Jeddah.

"It is a threat to the United States and it cannot continue." 

The new peace approach will have "both a security and political track simultaneously working in order to provide a comprehensive settlement", said Kerry, adding that Gulf states had "agreed unanimously with this new initiative".

He said details of the initiative would be finalised by the "parties themselves".

But the final agreement, in broad outline, would initially include a "swift formation of a national unity government with power shared among the parties".

It will also include the "withdrawal of forces from Sanaa and other key areas", and the "transfer of all heavy weapons including ballistic missiles and launchers from the Huthis and forces allied with them to a third party".

A Saudi-led Arab coalition in March last year launched a military campaign against Huthi rebels as they closed in on UN-backed President Abedrabbo Mansour Hadi in his southern refuge in Aden.

The intervention helped loyalists push the rebels out of five southern provinces, including Aden, but the rebels still hold onto many regions, including the capital Sanaa.

More than 6,600 people, mostly civilians, have been killed since March 2015 and more than 80 percent of the population has been left in need of humanitarian aid, according to the UN.